Method and apparatus for conditioning particulate materials



Sept. 10, 1968 E. c. TROY ET AL 3,400,916

METHOD AND APPARATUS FOR CONDITIONING PARTICULATE MATERIALS F'iled May4, 1966 5 Sheets-Sheet l FIG. 1

FW 30 I02 9a 42 I. I 38 P0 58a 96 i I II n m e4 I 22 560 r H, 'o

%I'Q-I O I O 94 7 $6 Iii I h .29 k

INVENTORS:

ELBERT C. TROY. ROBERT M. HUTCHINS ATT'Y Sept. 10, 1968 Filed May 4,1965 E. C. TROY ET AL METHOD AND APPARATUS FOR CONDITIONING PARTICULATEMATERIALS 5 Sheets-Sheet 2 ELBERT c, TROY, ROBERT M. HUTCIHINS Sept. 10,1968 E. OTROY ET AL METHOD AND APPARATUS FOR CONDITIONING PARTICULATEMATERIALS 5 Sheets-Sheet 5 Filed May 4, 1966 a l l l I l i l I i I I I aa I I ll FIG. 4

INVENTORS:

C O T Du U T H M T MR E 8 B L O E Du Sept. 10, 1968 E. c. TROY ET AL3,400,915

METHOD AND APPARATUS FOR CONDITIONING PARTICULATE MATERIALS 5Sheets-Sheet 4 Filed May 4, 19%

INVENTORS ELBERT C. TROY,

ROBERT M. HUTCIHINS ATT YS Sept. 10, 1968 E. c. TROY ET AL 3,400,916

METHOD AND APPARATUS FOR CONDITIONING PARTICULATE MATERIALS Filed May 4,1966 5 Sheets-Sheet 5 FIG. IO

INVENTORS. ELBERT C. TROY, ROBERT M. HUTCHINS ATT YS United StatesPatent 3,400,916 METHOD AND APPARATUS FOR CONDITION- ING PARTICULATEMATERIALS Elbert C. Troy, Highland Park, Ill., and Robert M. Hutchins,Mishawaka, Ind., assignors to National Engineering Company, Chicago,111., a corporation of Delaware Filed May 4, 1966, Ser. No. 547,555 35Claims. (Cl. 259147) The present invention relates to a new and improvedmethod and apparatus for conditioning particulate materials, such asfoundry sand, granular materials, powdered materials, and the like.

A problem often encountered in foundry operations is that of rapidly andefficiently heating and mixing batches of foundry sand to elevatedtemperatures of approximately 300 F. so that bonding materials can thenbe easily blended into the batch to coat the sand granules.

It is an object of the present invention to provide a new and improvedmethod and apparatus for conditioning particulate materials, such assand, granular and powdered materials and the like.

More specifically, it is an object of the present invention to provide anew and improved method of rapidly and efficiently heating particulatematerials, such as foundry sand, granular and powdered materials, andthe like.

It is another object of the invention to provide a new and improvedmethod of heating particulate materials which insures a thorough andintimate mixing of the materials providing a substantially uniformtemperature throughout.

Another object of the invention is the provision of a new and improvedmethod of mixing particulate materials.

Still another object of the invention is the provision of a new andimproved method of rapidly, thoroughly, and intimately mixingparticulate materials with a minimum amount of mechanical energyexpended.

Still another object of the invention is the provision of a new andimproved method of conditioning particulate materials which employsprimary direct heating of a fractional portion of the materials whilethe particles are in an individually separated condition, and thereafteremploys surface contact between the heated particles to produce asecondary heat transfer and insure uniformity of temperature throughoutmaterial being conditioned.

Yet another object of the invention is the provision of a new andimproved method of conditioning particulate materials employing theprinciple of relative movement between a source of heat and a fractionalportion of the material, wherein the particles are separated from eachother during heating and then are returned over stationary heatingsurfaces to a gravity compacted condition to effect heat transfer to theremaining portion of material.

Yet another object of the present invention is the provision of a newand improved method of treating particulate materials which is capableof rapidly elevating the temperature of the materials to the desiredlevel.

Another object of the invention is the provision of a new and improvedapparatus for rapidly and efiiciently heating particulate materials,such as foundry sand, various granulated and powdered materials, and thelike.

Yet another object of the present invention is the provision of a newand improved apparatus for rapidly and efficiently heating particulatematerials while thoroughly and intimately mixing the same to insureuniformity of temperature and consistency throughout.

Another object of the present invention is to provide a new and improvedapparatus for thoroughly and intimately mixing particulate materialswith a minimum of 3,400,916 Patented Sept. 10, 1968 energy expended anda minimum of wear resulting on the apparatus.

Yet another object of the invention is the provision of a new andimproved apparatus for heating and mixing particulate materials capableof rapidly and efliciently heating and mixing even the most finelydivided materials, including those having relatively low heat absorptioncharacteristics.

Still another object of the invention is the provision of a new andimproved apparatus for conditioning and treating particulate materialsincluding means for rapidly moving the material around a chamber whilelifting and maintaining a fractional portion of the material in acondition wherein the individual particles are separated from oneanother, and means for directing heated gases into the fractionalportion of material so separated before the particles are returned to agravity compacted condition with the remaining material.

Yet another object of the invention is the provision of a new andimproved apparatus for intimately and thoroughly mixing particulatematerials as described above, including means for dividing the separatedparticles of material into a plurality of streams and then reuniting thematerial with a common mass.

Still another object of the invention is the provision of a new andimproved apparatus for treating particulate materials capable of rapidlyelevating the temperature of the materials to the desired level.

A further object of the invention is to provide a new and improvedapparatus for treating particulate materials of the type described whichis low in cost, relatively simple in construction, reliable in operationand economical to operate.

These and other objects and advantages of the present invention areachieved by the provision of a new and improved method of treatingmaterial comprising the mixing of a mass of particulate material bycircular spiraling movement around a confined area and continuallylifting or elevating a fractional portion of the material above thelevel of a remaining portion. The individual material particles of theelevated fractional portion of material are separated from one anotherto expose maximum surface areas thereof to the surrounding: atmosphereand, while in such separated or exposed condition, are subjected to adirect blast of heated gases to effect a rapid and efiicient heatingthereof. The particles are returned to the remaining mass of material invarious diverse and reuniting streams and reach a gravity compactedcondition in the particles and remaining material wherein conductiveheat transfer takes place between the particles to effect a uniformtemperature throughout the material being treated.

Briefly, the apparatus of the present invention comprises a circularmixing chamber having a bottom and a sidewall and annular baffle meansare mounted in the chamber spaced above the bottom and extendinginwardly toward a central upstanding axis of the chamber. The bafliemeans includesa plurality of individual, spaced apart bafiie membershaving surfaces. inclined relative to the bottom of the mixing chamber.A mixing head is mounted in the chamber for rotation about the centralaxis and the head includes plow means radially outward of the centralaxis and movable around the chamber below the annular baffie means forlifting and elevating a fractional portion of the material upwardlythrough the openings between the individual baffle members. As thematerial is elevated, the bafile members help to separate the particlesof material from one another so that above the baffle means the materialparticles are in an exposed or widely separated condition. The liftedmaterial particles drop downwardly by gravity toward the baffle meansand are separated into various diverse streams and reunited as theparticles flow downwardly toward the bottom of the mixing chamber.Burner means are provided for supplying heat to the material in themixing chamber and the burner means includes a movable nozzle structurehaving an outlet end positioned to move around the chamber adjacent thelevel of the baffle means. The nozzle structure is mounted for rotationwith the mixing head and the outlet thereof is positioned to produce ahigh velocity flow of heated gases for direct contact with the materialflowing down through and below the baffle means. Accordingly, theindividual particles returning toward the bottom of the mixing chamberare enveloped in high temperature gases from the nozzle outlet andabsorb large quantities of heat. These heated particles eventually reachthe material in the lower portion of the mixing chamber below the bafflemeans in a gravity compacted condition, and heat transfers from thehotter particles of material to the cooler ones by direct conduction asthese particles are thoroughly and intimate-1y mixed traveling aroundthe chamber.

For a better understanding of the present invention, reference should behad to the following detailed description taken in conjunction with thedrawings, in wtich:

FIG. 1 is a side r-levational view of a new and improved apparatus fortreating particulate materials constructed in accordance wtih thefeatures of the present invention;

FIG. 2 is a vertical cross-sectional view taken through the centralportion of the apparatus of FIG. 1;

FIG. 3 is a transverse cross-sectional view taken substantially alongline 33 of FIG. 2;

FIG. 4 is a transverse cross-sectional view taken substantially alongline 4-4 of FIG. 2;

FIG. 5 is an enlarged, fragmentary, sectional view taken substantiallyalong line 55 of FIG. 3 and illustrating in detail the construction ofbafile members of the present invention;

FIG. 6 is an enlarged, fragmentary, sectional view similar to FIG. 3illustrating a portion of the bathe means of the present invention, inplan view;

FIG. 7 is an enlarged, fragmentary, sectional view similar to FIG. 2taken substantially along line 77 of FIG. 3.

FIG. 8 is an enlarged, detailed, fragmentary, crosssectional view takensubstantially along line 88 of FIG. 3;

FIG. 9 is an enlarged, fragmentary, cross-sectional view takensubstantially along line 9-9 of FIG. 3 and illustrating somewhatschematically the lifting and heating action of the apparatus;

FIG. 10 is an enlarged, fragmentary, cross-sectional view, similar toFIG. 9, taken substantially along line 10-10 of FIG. 3; and

FIG. 11 is an enlarged, fragmentary, sectional view taken substantiallyalong line 11-11 of FIG. 4.

Referring now, more particularly, to the drawings, therein isillustrated a new and improved apparatus for treating particulatematerial constructed in accordance with the present invention andindicated generally by the reference numeral 20. The apparatus 20includes a large, insulated, enclosed mixing chamber 22 which issupported from the floor or other structure by a leg structure 24 whichhouses and supports a power driving assembly 26 (FIG. 2) for driving amixing head assembly 28 mounted for rotation in the mixing chamber.Particulate material to be treated is introduced into the mixing chamber22 through an inlet chute 30 having a movable inlet door or gate 32 tocontrol the flow of material through an inlet opening in the top of themixing cham ber. After treatment in the mixing chamber 22, the materialis discharged through an outlet chute 34 supported by the leg structure24 and having a movable discharge door or gate 36 for controllingoutflow of material through an opening in the bottom of the mixingchamber. In order to supply heat to the material in the mixing chamber,a gas or oil burner 38 is mounted on the top wall of the chamber todirect heated gases downwardly into the chamber for distribution by themixing head assembly 28 through a curved nozzle structure 40 mountedthereon. Exhaust gases, water and other products of combustion areremoved from the enclosed mixing chamber 22 through an exhaust stack orvent pipe 42 which extends upwardly from the chamber and may beconnected with suitable dust collector equipment (not shown) forremoving any fine particulate materials carried by the exhaust gases.

Describing the mixing chamber 22 in greater detail, the chamber includesa circular bottom wall or inner wear plate 44 having a centrally locatedaperture 46 therein to accommodate an upstanding drive axle or shaft 48of the mixing head assembly 28. The bottom wall 44 is formed with agenerally rectangular discharge opening 50 adjacent the perimeterthereof to accommodate the movable discharge door 36 which, when in ,aclosed position (solid lines, FIG. 2), is level with the upper surfaceof the bottom wall and forms a portion of the bottom wall of the mixingchamber 22. The mixing chamber includes an upstanding sidewall 52comprising a lower frustoconical section 54 joined to the outerperimeter of the circular bottom wall 44 and sloped to extend upwardlyand outwardly thereof, and an upper cylindrical section 56 joined to theupper end of the lower section 54. The slope of the lower section 54 isapproximately degrees to the bottom 44 in order to help direct thematerial inwardly toward the central portion of the mixing chamber andthe junction between the upper and lower sections of the sidewall 52 isapproximately midway between the upper and lower ends of the mixingchamber. Normally, the mixing chamber 22 is filled with particulatematerial to a level somewhat below the junction between the upper andlower sections 56 and 54, leaving the upper portion of the chamber opento accommodate a relatively large volume of hot gases introduced intothe chamber by the burner assembly 38. The upper end of the mixingchamber 22 is closed by a removable top wall 58 having a central opening60 therein to accommodate the downward discharge from the burnerassembly 38. The top wall is held in place by a number of cap screws 62which extend downwardly into an angular rim 64 at the upper end of theupper sidewall section 56, and after removal of these screws the topwall can be lifted off to open the interior of the chamber forinspection or maintenance if necessary. In addition to the centralburner opening 60, the top wall includes a rectangular opening 66 incommunication with the inlet chute 30 for receiving material therefrom,and a circular vent or exhaust opening 68 is provided to communicatewith the lower end of the exhaust stack 42.

Because large quantities of heat are introduced into the mixing chamber22, the outer surfaces thereof are insulated by a layer 70 of suitableinsulating material, such as fiber glass or the like, and the insulatingmaterial is protected against damage by sheet metal coverings 44a, 54a,56a, and 58a corresponding generally in shape to the adjacent mixingchamber wall surfaces 44, 54, 56 and 58. Because of the excellentinsulation provided, heat losses to the atmosphere from the mixingchamber 22 are reduced and minimized; however, if not heating is to takeplace in the chamber, the insulation and sheet metal protectivecoverings can be dispensed with.

The leg structure 24 includes a rectangular boxlike housing 72 havingshort supporting legs 74 extending, downwardly from the corners thereof,and the housing encloses a power driving assembly connected to drive thedrive shaft 48 of the mixing head assembly 28. To this end, the lowerend of the drive shaft is supported in a tubular sleeve 76 having aflanged upper end 76a bolted to the underside of the mixing chamberbottom wall. The lower end of the drive axle 48 extends below the lowerend of the sleeve 76 and is directly coupled to the output shaft of aspeed reducer 78 (FIG. 2) which, in turn, is driven by an electric motor80 through belt drive system 82. The motor 80, belt drive system 82, andspeed reducer are enclosed within the housing 72 and opposite sidewallsthereof are formed with grilled openings 84 (FIG. 1) to permit aventilating airflow to cool the motor and speed reducer. The dischargechute 34 is supported by one of the sidewalls of the leg structurehousing 72, and an adjacent sidewall thereof provides support for abracket 86 which pivotally supports one end of an air cylinder 88 forcontrolling the discharge gate 36. The discharge gate is supported on anaxle 90 mounted on a pair of brackets 92 depending from the underside ofthe mixing chamber 22, and the axle 90 protrudes outwardly from one sideof the discharge chute 34 'for connection with the movable piston rod88a of the door cylinder through a lever 94. Pressurized fluid flow intothe cylinder 88 is controlled by a conveniently located control system(not shown) so that the discharge gate 36 can be opened and closed asdesired.

Referring to the inlet chute 30 and inlet gate 32, the gate is supportedon an axle 96 mounted in hearing assembles 98 on the sidewalls of thechute. The axle 96 protrudes outwardly through the chute sidewalls and apair of lever arms 100 (FIG. 1) are connected to the outer ends thereoffor supporting movable weights 102 which bias the gate to a closedposition. The upper edge of the inlet gate 32 is sealingly connected toa baffle plate 104 in the inlet chute by a flexible seal 106 of heatresistant material, such as asbestos or the like. The arms 100 andweights 102 normally bias the inlet gate to a closed position (solidlines, FIG. 2); however, when a batch of particulate material is dumpedinto the inlet chute, the weight of the material causes the gate to moveto the open position (dotted lines, FIG. 2) and the material flows intothe mixing chamber 22 through the inlet opening 66. After the rnaterialhas entered the chamber, the inlet gate 32 then moves back to the closedposition and seals off the inlet opening 66 to prevent the escape ofheated gases in the mixing chamber. To this end, suitable stationaryseals or stops 106 are provided around the inner surfaces of the inletchute 30, as shown in FIG. 2, to seal against the edges of the inletgate 32 when in a closed position.

Turning to the structure interiorly of the mixing chamber 22, there isprovided in accordance with the present invention, an annular ring 110of inwardly extending baflle members or vanes 112 positioned adjacentthe level of the junction between the lower frustoconical section 54 andupper section 56 of the mixing chamber sidewall 52. The bafile members112 are supported by a relatively deep outer band or ring 114 and anarrower inner ring or band 116 which are concentric with the centralaxis of the chamber and mixing head drive shaft 48. The bands or rings114 and 116 may be segmented, if desired, to facilitate assembly anddisassembly, and the lower end of the outer ring 114 rests against theinwardly sloping section wall 54 for support of the baffle assembly.

The outer ends of the individual baflle members 112 are fastened to theouter ring 114 and the inner ends of the bafile members are secured tothe smaller inner ring 116. The upper edges of the baffle members extendgenerally horizontally inwardly of the outer sidewall 56 of the mixertoward the central portion thereof, and are arranged in plan view, asbest shown in FIG. 3, with their inner ends positioned in advance orahead of their outer ends in the direction of rotation of the mixinghead assembly 28, as indicated by an arrow 118; thus the vanes could bedescribed as being askew in relation to radii extending outwardly fromthe central axis of rotation of the mixing head.

Preferably, the baffies 112 are for-med of heat-conducting metal, suchas stainless steel, aluminum, or the like and are cut and bent to shapein a stamping operation.

As best shown in FIGS. 5, 9, and 10, each baffle 112- is formed into anangular cross section with a pair of oppositely and downwardly extendingsurfaces 112a and 112b integrally joined together at their upper edgesto form an apex 112a along the upper edge of the baflle member as awhole. The inclined surfaces 11212 of the bafiies are considerablylarger in area than the surfaces 112a and the lower edges of the smallersurfaces are adapted to lie in spaced facing relation to the largersurfaces 112b along a line positioned downwardly of the apex 1120.Spacing between the lower edges of the smaller baffle surface portions112a and the larger surface portions 112b of adjacent baffle members isobtained by means of a plurality of upwardly extending spaced apartprojections or bosses 112d (FIG. 8), and adjacent baflie members arewelded together at the projections to form the annular bafile structure.Because of the spacing, a plurality of narrow slots or openings 120 areformed between adjacent baffie members 112 to permit material to flowupwardly and downwardly through the bafiie assembly, as best shown inFIGS. 9 and 10. The slots 120 are narrow enough in width to retard thedownward flow of material therethrough but are wide enough so thatindividual grains or granules of the material will pass. Accordingly,several baflie assemblies may be provided for insertion in the mixingchamber, having different openings between baffles 112 to accommodatethe types of material being treated.

Energy for forcing the material beneath the baflle assembly in the lowersection of the mixing chamber upwardly through the slots 120 isfurnished by the mixing head assembly 28 as it rotates around thechamber. To this end, the mixing head assembly includes an upper andouter plow or scraper 122 having an upper edge 122a positioned to movein close proximity to the lower edges of the bafile surface members1121), as best shown in FIGS. 9 and 11. The plow 122 includes an outeredge 122b which is sloped to be parallel with and move in closeproximity to the frustoconical wall section 54 of the mixing chamber.The plow 122 is supported on a downturned portion at one end of a crossarm 124 which is carried by a turret head 126 On the upper end of thedrive shaft 48 of the mixing head assembly. The opposite end of thecross arm 124 provides support for an elongated, curved upper flow 128positioned midway between the underside of the bafile structure 110 andthe mixer bottom wall 44. As illustrated in FIGS. 3 and 4, the plow 122is in angular relation with the radial axis of the cross arm 124, andthe outer edge 12212 of the plow is advanced from the cross arm in thedirection of rotation of the mixing head.

The turret head 126 of the mixing head assembly also provides supportfor a pair of lower plow members 130 and 132 which move along thecircular bottom wall 44 to continually mix the material in the center ofthe mixing chamber. The inner plows 130 and 132 are supported on a pairof downwardly extending angle brackets 134 bolted to the turret head 126by cap screws 136 (FIG. 2), and the plows extend outwardly toward theperiphery of the mixing chamber to move the material outwardly as themixing head 28 rotates.

The turret head 126 also provides support for the movable nozzlestructure 40 which directs the downwardly moving high velocity hot gasesfrom the burner 38 outwardly toward the sidewall 52 of the mixingchamber 22. The nozzle structure 40 comprises a tubular elbow of heatresistant material having a pair of mounting feet 400 (FIG. 1) whichrest upon the top of the turret head 126 and are secured thereto by apair of removable cap screws 136. The discharge end of the nozzlestructure 40 extends horizontally outwardly from the central axis of themixing chamber (FIG. 2), and the nozzle includes an upstanding inletportion in concentric alignment with the downward discharge axis of theburner 38. Because of relative rotation between the burner 38 and therotating nozzle structure 40, the upper end of the nozzle structure isopen to accommodate a downwardly protruding portion 38a of the burner.The opening 60 is somewhat larger than the outer diameter of the burnerdischarge nozzle 38a to permit outside air to be drawn into the nozzlestructure 40 by venturi action when the burner is in operation. Theheated gases from the burner 38 flow downwardly in the upstanding inletportion of the nozzle structure 40 and are directed radially outward inthe direction of the arrow 138 in FIG. 2. These hot gases are directedat high velocity against the material moving through the bafilestructure 110 and against the lower portion of baflle members 112b whichare out out, as shown in FIGS. 2, 7 and 11, in order that the outlet endof the nozzle structure 40 may move in close proximity thereto, as bestshown in FIG. 7. The nozzle structure 40 is positioned on the mixinghead 28 so that the outwardly extending outlet portion is angularlydisplaced with respect to the cross arm 124 and outer plow 122 in adirection generally opposite to the direction of mixing head rotation(arrow 118) as best shown in FIG. 3.

In operation, the mixing chamber 22 is filled with a quantity or batchof particulate material, such as sand or the like, which is to betreated to a level somewhat below the underside of the annular bafflestructure 110. After filling, the inlet gate 32 moves to a closedposition sealing off the upper end of the mixing chamber. As the mixinghead assembly 28 is rotated, the lower inner plows 130 and 132 rapidlymix and agitate the material adjacent the circular bottom wall 44 andmove the material outwardly toward the sloping frustoconical wallsection 54. The upper, inner plow 128 pulls the material back inwardlytoward the central portion of the mixing chamber and provides a feedingtype action to resupply the lower plows 130 and 132 so that thematerial, while being moved in a generally circular pattern around themixing chamber is also rolled inwardly and pushed outwardly as themixing head rotates.

The outer plow 122 moves at a velocity somewhat greater than the otherplows because of its greater distance from the central axis of thechamber, and as it moves in close proximity to the frustoconicalsidewall section 54 and underside of the annular bafile structure 110, afractional portion of the material is forced or 'lifted upwardly throughthe narrow slots 120 between the adjacent baflle members 112. Thelifting action causes the individual particles or granules of thematerial to be separated from one another in an aerating type action,and the particles are divided into various diverse streams by thesloping surface members 112b of the baffles, as shown in FIG. 9. Some ofthe particles strike the oppositely sloping baffle surface members 112aand are directed downwardly into the upwardly moving streams in areuniting action and the streams pass upwardly through the narrow slots120 in the annular baflle structure 110.

The mixing head assembly is driven at speeds ranging from 50 to 60r.p.m. producing velocities of around 1000 to 1200 f.p.m. for the outerplow 122 in a mixing chamber having a diameter of approximately sixfeet. In viewing the apparatus in operation it appears as if afractional quantity of the material in the chamber is literally beingexploded upwardly through the annular battle assembly 110 in thevicinity of the outer plow 122. And as the plow moves around the baffleassembly it appears that an explosive wave of material is moving aroundthe chamber when viewed from above. The material exploded upwardlythrough the slots 120 by the plow 122 comprises a fractional portion ofthe total quantity of material in the mixing chamber being treated, andthe material begins to fall back downwardly toward the annular baffieassembly 110 after the plow 122 has passed underneath. The materialfalling downwardly strikes the apexes 1120 of the baffle members 112 andis divided into oppositely flowing streams by the surfaces 112a and11211, and these streams collect in the troughs between adjacent bafilemembers and the particles flow downwardly through the narrow slotsbehind the moving plow 122, as shown in FIG. 10.

The lifting and aeration of the material traveling upwardly through thenarrow slots and the dividing, reuniting, and dividing action of thebaffie members 112 on the upwardly and downwardly traveling material,provides for excellent mixing action to insure uniform consistency ofthe material when the apparatus is used in dry blending operation. Thecontinual mixing action of the material below the baffle assembly by theplows 128, 130 and 132 insures that the fractional portion of thematerial lifted by the upper plow 122 is thoroughly and intimatelyblended with the mass of material in the bed or lower section of themixing chamber. The sloping wall section 54 also aids greatly in themixing process in returning the material falling through the slots ofthe bafile ring back toward the control portion of the mixing chamber.

The outlet end of the nozzle structure 40 is positioned to direct a highvelocity flow of heated gases directly into the material that has beenelevated and lifted by the plow 122 and is passing back through theslots and downwardly into the material beneath the baffle assembly 110in the bed of the mixing chamber. Because the baffle members 112 areconstructed of material having good heat conductivity characteristicsand because the nozzle structure outlet is positioned to direct aportion of its discharge directly against the lower portions of thebafile member surfaces 112b, as best shown in FIG. 7, the baffle members112 become heated as the nozzle structure rotates around the chamber.Accordingly, as the particles or granules of material pass upwardly anddownwardly through the heated bafile assembly 110 in contact with thebaffle surfaces 112a and 1121), direct heat transfer by conduction takesplace and the particles of material are elevated in temperature. Greaterheat transfer is effected because the particles are separated into thinstreams passing over the baffle surfaces and are retarded somewhat ontheir downward travel through the slots 120 by the collecting action onthe upper troughs formed by baflle surfaces 112a and 112b of adjacentbafile members.

The heated gases from the nozzle structure outlet also flow upwardlythrough the narrow slots 120 in the annular baflle structure 110 andsubject the separated individual particles and granules passingtherethrough to intense heat. Because of the separating or aeratingaction during lifting and falling of the particles of material throughthe baffle structure and the direct and enveloping contact between theparticles so moving and the high velocity hot gases from the nozzlestructure 40, a rapid heat exchange process is effected between thematerials and the gases, causing the temperature of the material to berapidly elevated. Even materials such as foundry sand having relativelylow heat conductivity can be rapidly heated in this manner.

The heated material falling downwardly from the baffle structure 110returns to the material remaining in the bed of the mixing chamber andis thoroughly and intimately intermixed therewith by the plows 128, and132, and during this process heat is transferred from the hotterparticles to the colder ones by direct conduction. Because the materialin the bed of the mixing chamber is in a gravity compacted condition,good contact is obtained between the individual hotter and colderparticles, and the thorough and intimate continuous mixing achieves auniform temperature throughout the entire mass.

It is believed that the highly efiicient heat transfer is effected intwo stages comprising the primary direct application of the hot gases tolifted and separated ever changing fractional portions of the materiallifted by the plow and passing through the heated baffie structure invarious diverse thin streams. A secondary heat transfer is effected asthe heated streams of particles return to the gravity compacted mass inthe mixing chamber below the baflie structure and are thoroughly andintimately mixed with the colder particles.

In an apparatus constructed in accordance with the present invention forhandling SOD-pound batches of foundry sand and using a burner capable ofsupplying 1,000,000 B.t.u.s per hour, it was found that the sand batchcould be heated from an ambient temperature of 8090 F. to approximately300-350 F. within a time period of less than three minutes. Also, it wasfound that extremely high heat transfer efiiciencies (in the range of 70to 80%) were attained with the apparatus.

The apparatus 20 of the present invention is extremely useful inblending dry materials together into a mixture having a uniformconsistency throughout and, more importantly, is useful for rapid andefiicient heating of material having low heat absorptioncharacteristics. Specifically, the invention is useful in foundryoperations for rapidly heating batches of used foundry sand in order tocarbonize the coating materials thereon. The apparatus is extremelyreliable in operation and very little mechanical wear occurs, greatlyreducing the maintenance required. In previous types of batch heatersfor sand and other abrasive material, mechanical Wear comprises a majorproblem, necessitating frequent maintenance and repair. In the presentinvention wear occurs mainly on the outer plow 122, which is easilyreplaceable, and because there is no direct engagement between movingparts, such as chains and sprockets, etc., commonly used in other typesof heaters for moving the material, the present invention offers manyoperating advantages in addition to the extremely high heat transferefiiciencies obtainable.

While there has been illustrated and described a single embodiment ofthe present invention, it will be appreciated that numerous changes andmodifications will occur to those skilled in the art, and it is intendedin the appended claims to cover all those changes and modificationswhich fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. Apparatus for conditioning particulate material comprising a mixingchamber having a bottom and a sidewall, annular bafile means in saidchamber spaced upwardly from said bottom and extending inwardly of saidsidewall toward an upstanding central axis in said chamber, said bafiiemeans including a plurality of spaced apart baflle members havingsurfaces inclined relative to said bottom, and a mixing head in saidchamber mounted for rotation about said central axis and including plowmeans radially outward of said axis and movable around said chamberbelow said bafile means for lifting a portion of said material in saidchamber upwardly through said bafile means upon rotation of said mixinghead in one direction.

2. The apparatus of claim 1 wherein said inclined surfaces include firstsurfaces sloped upwardly away from said bottom in a direction generallythe same as the direction of movement of said plow means around saidchamher.

3. The apparatus of claim 2 wherein said inclined surfaces includesecond surfaces sloped in a direction opposite to that of said firstsurfaces.

4. The apparatus of claim '3 wherein said baffle members are integrallyformed of angular cross section including longitudinal upper apexesformed along the junction of said first and said second inclinedsurfaces and extending inwardly of said sidewall.

5. The apparatus of claim 4 wherein said second surfaces of said bafilemembers are smaller in dimension between a said apex and a lower edgethereof than said first surfaces, and said lower edges are fixed innarrow spaced relation away from the first surfaces on adjacent bafflemembers along a position intermediate said apex and the lower edges ofsaid first surfaces.

6. The apparatus of claim 5 wherein said first surfaces includeintegrally formed spaced apart projections thereon engaging the loweredges of said second surface on adjacent baflle means.

7. The apparatus of claim 4 wherein the upper apexes of said bafflemembers are angularly disposed in relation to radial planes extendingoutwardly from said central ax1s.

8. The apparatus of claim 7 wherein the inner ends of said bafflemembers are forward of the outer ends thereof in respect to the generaldirection of movement of said plow means.

9. The apparatus of claim 8 wherein said plow means includes anadvancing face angularly disposed in relation to the apexes of saidbafile members with the outer edge of said plow means forward of theinner portions of said baffle members in respect to the generaldirection of movement thereof.

10. The apparatus of claim 1 wherein said bafile means includes innerand outer concentric support rings for supporting the inner and outerends of said bafiie members.

11. The apparatus of claim 1 wherein said mixing chamber sidewallincludes a lower frustoconical section sloping upwardly and outwardly ofsaid bottom and an upper section angularly joined with the upper end ofsaid lower frustoconical section.

12. The apparatus of claim 11 wherein said baffle means is positionedadjacent the junction of said upper and lower sections of said sidewalland extends inwardly thereof toward the central portion of said mixingchamber.

13. The apparatus of claim 12 wherein said plow means includes an upperedge moving in close proximity to the underside of said baffie means anda sloping outer edge moving in close proximity to said lowerfrustoconical wall section.

14. The apparatus of claim 11 including lower plow means positioned tomove material adjacent the bottom of said mixing chamber outwardlytoward said lower section of said sidewall.

15. Apparatus for treating particulate material comprising a mixingchamber having a bottom and a sidewall, annular baflle means in saidchamber spaced upwardly from said bottom and extending inwardly of saidsidewall toward an upstanding central axis of said chamber, said bafflemeans including a plurality of spaced apart baffie members havingsurfaces inclined relative to said bottom, a mixing head in said chambermounted for rotation about said central axis and including plow meansradially outward of said axis and movable around said chamber below saidbafile means for lifting a portion of the material in said chamberupwardly through said baffle means upon rotation of said mixing head inone direction, and burner means for supplying heat to the material insaid chamber including nozzle means extending outwardly toward saidsidewall adjacent the level of said baffle means and rotatable with saidmixing head round said chamber for directing heated gases into thematerial moving through said baflie means.

16. The apparatus of claim 15 wherein said nozzle means includes anoutlet for discharging heated gases positioned behind said plow means inrespect to the di rection of movement thereof around said chambers.

17. The apparatus of claim 16 wherein the inclined surfaces of saidbafiie members include second surfaces sloped in a direction opposite tothat of said first surfaces.

18. The apparatus of claim 17 wherein said baffle members are integrallyformed of angular cross section including longitudinal upper apexesformed along the junction of said first and second inclined surfaces andextending inwardly of said sidewall.

19. The apparatus of claim 18 wherein said second sur- 11 faces aresmaller in dimension between said apex and a lower edge thereof thansaid first surfaces, and said lower edges are fixed in narrow spacedrelation away from the first surfaces on adjacent battle members along aposition intermediate said apex and the lower edges of said firstsurfaces.

20. The apparatus of claim 16 wherein said nozzle outlet is positionedto move under and in close proximity to inner portions of said bafflemembers.

21. The apparatus of claim 16 wherein said mixing chamber includes a topwall and said burner means includes a fixed portion centrally positionedon said top wall to discharge hot gases downwardly into said nozzle fordirection outwardly thereby toward said sidewall.

22. The apparatus of claim 21 wherein said nozzle means is fixedlymounted on said mixing head and includes an upstanding leg axiallyaligned with the discharge of said fixed portion of said burner means.

23. The apparatus of claim 22 including means for introducing ambientair into said nozzle means between said upstanding leg and said fixedportion of said nozzle means.

24. The apparatus of claim 15 wherein the inclined surfaces of saidbaffle members include first surfaces sloped upwardly away from saidbottom in a direction generally the same as the direction of movement ofsaid plow means around said chamber.

25. The apparatus of claim 15 wherein said mixing chamber sidewallincludes a lower frustoconical section sloping upwardly and outwardly ofsaid bottom and an upper section angularly joined with the upper end ofsaid lower section.

26. The apparatus of claim 25 wherein said annular baffle means ispositioned adjacent the junction of said lower and upper sidewallsections and extends inwardly thereof toward the central portion of saidchamber.

27. The apparatus of claim 25 wherein said flow means includes an upperedge moving in close proximity to the underside of said baffle means anda slopping outer edge moving in close proximity to said lowerfrustoconical sidewall section.

28. A method of treating particulate material comprising mixing a massof said material by circular movement around a confined area, lifting afractional portion of said mass upwardly above the remaining portion,dropping said lifted fractional portion of material to return back tosaid remaining portions, dividing said dropping fractional portion ofmaterial into plural streams, and retarding the downward velocity ofsaid diverse streams above said remaining portion of said material mass.

29. The method of treating particulate material of claim 28 wherein saidplural streams of material are directed in diverse directions.

30. The method of treating particulate material of claim 28 wherein saidlifting separates individual particles of said material from oneanother.

31. The method of treating particulate material of claim 28 includingthe step of directly applying heated gases to said fractional portion ofmaterial lifted above said remaining portion of said mass.

32. The method of treating particulate material of claim 31 wherein saidheated gases are directed into said material falling in plural streamsback to said mass.

33. A method of heating a quantity of particulate material comprisingthe steps of confining a first portion of said material in a gravitycompacted condition in a heat insulated area, separating the particlesof a fractional portion of said material from one another and from thegravity compacted portion, subjecting said separated fractional portionof material to directly applied heated gases raising the temperature ofsaid particles, and returning said heated particles to a gravitycompacted condition with direct contact between said particles and withsaid first portion of material.

34. The method of heating particulate material of claim 33 including thestep of dividing and reuniting said separated particles during theapplication of heated gases thereto.

35. The method of heating particulate material of claim 34 wherein saidseparated particles are subjected to direct heated gases during theirreturn to said gravity compacted condition.

References Cited UNITED STATES PATENTS 2,188,798 1/1940 Smith 25915l2,264,610 12/1941 Beardsley 259l47 2,314,486 3/1943 Dvorak 34l8l2,760,244 8/1956 Mcllvaine 259-451 3,348,819 10/1967 McIlvaine 259l51ROBERT W. JENKINS, Primary Examiner.

28. A METHOD OF TREATING PARTICULATE MATERIAL COMPRISING MIXING A MASSOF SAID MATERIAL BY CIRCULAR MOVEMENT AROUND A CONFINED AREA, LIFTING AFRACTIONAL PORTION OF SAID MASS UPWARDLY ABOVE THE REMAINING PORTION,DROPPING SAID LIFTED FRACTIONAL PORTION OF MATERIAL TO RETURN BACK TOSAID REMAINING PORTIONS, DIVIDING SAID DROP-